SKYLIVE/EARTHSKY
Comet C/2021 A1 Leonard’s trajectory as it enters the interior of the Solar System, approaches Earth, reaches its closest point to the Sun, and then returns away from Earth. During December 14 to the end of December 2021, comet Leonard can be seen just after dusk in the southwest direction with the help of binoculars or a simple telescope.
Comet C/2021 A1 finally reached its closest point to Earth on Sunday (12/12/2021). Now, the comet is moving closer and closer to the Sun and will risk its life, whether it survives or is destroyed.
Comet Leonard, as quoted from Space, Sunday (12/12/2021), was first discovered by Gregory J Leonard of the Mount Lemmon Observatory in Tucson, Arizona, United States, on January 3, 2021. At that time, the comet was at a distance of 750 million kilometers (km) or 5 units astronomy (AU). The astronomical unit is a representation of the average distance between the Sun and the Earth of 150 million km.
Since its discovery, Comet Leonard has continued to approach Earth and is expected to provide a beautiful view for observers of the night sky on Earth. Sunday (12/12/2021), Leonard reached his closest point to Earth, which is at a distance of 35 million km from Earth. Leonard’s closest approach to Earth is 91 times the Earth-Moon distance.
Although very close, the comet’s brightness or magnitude of 5 makes this comet too weak to be seen with the naked eye. Not to mention its fairly low position near the horizon. However, this comet can be observed with the help of a simple telescope or binoculars.
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Now, comet Leonard is moving toward the Sun. The closest distance to the Sun or the comet’s perihelion is expected to be reached on January 3, 2022 at a distance of 90 million km. Generally, as the comet gets closer to the Sun, the comet gets brighter. Therefore, this month is the best time to observe Leonard.
Observation
Comet Leonard is predicted to be the brightest comet of the year. However, the time window for observing this comet is limited. When the comet is near its closest point to Earth, this is the best time to observe the tailed star.
During early December 2021, this comet can be seen in the early hours of the morning before dawn. However, its position will be lower or closer to the horizon. This means that the observation challenge will be even greater because the light of the comet will be increasingly obscured by the light of dawn.
Andi Pangerang from the Center for Space Research, National Research and Innovation Agency (formerly part of the National Institute of Aeronautics and Space), said that from Indonesian territory, Comet Leonard on December 1-11 2021 can be seen in the northeast direction just before dawn.
From the territory of Indonesia, comet Leonard on December 1-11 2021 can be seen in the northeast direction just before dawn.
On December 1, 2021, the comet’s altitude will reach about 30 degrees. However, this altitude continued to fall over time until it was only about 10 degrees on December 11, 2021.
Compass
Comet C/2021 A1 Leonard is seen through a telescope in this photo released on December 9, 2021. Comets coming from the farthest reaches of the solar system will pass “very close” to Earth, at 35 million kilometers, and their long tail will be visible in the northern hemisphere. , according to the Paris-PSL Observatory.
As quoted from Sky & Telescope, Friday (12/3/2021), the comet will move across the constellations Canes Venatici, Bootes, and Serpens Caput during early December. On December 10-13, 2021, the comet will be in the constellation Ophiucus.
On December 12-13, 2021 or when it reaches its closest distance to Earth, Comet Leonard cannot be observed because its position is too close to the Sun or too low.
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After reaching the closest distance to Earth, the comet’s observation time changes. From December 14, 2021 until the end of the month, the comet will be visible after sunset, after the sunset has disappeared.
The comet’s visible location will be in the southwest where its altitude will continue to increase until it reaches a maximum of about 35 degrees before Leonard reaches his closest point to the Sun. Over this period, the location of the comet will change from the background of the constellations Serpent, Sagittarius, Microscopium, to Piscis Austrinis.
However, the weather is the main problem to be able to observe comet Leonard in Indonesia. Since early December 2012, a number of observatories in Indonesia have been on standby to photograph this comet, ranging from the National Observatory of Mount Timau in Kupang, East Nusa Tenggara, to the Astronomical Observatory of the Lampung Sumatra Institute of Technology. The same thing is done by amateur astronomers and private observatories.
However, no images of comet Leonard have been obtained yet. In addition to cloudy and rainy, photographing celestial bodies, especially those that are dim and located near the horizon, is not an easy matter. However, they still hope that at least until the end of the year there will be images of comet Leonard obtained from Indonesia.
dim
Comet light usually gets brighter as it approaches the sun. This condition occurs because the closer to the Sun, the heat from the Sun will heat up the surface of the comet’s core to burn more gas and dust. As a result, in addition to getting brighter, the comet’s tail will be longer.
However, something different happened to comet C/2021 A1. As quoted from Space, Thursday (9/12/2021), the appearance of comet Leonard’s image obtained since late November 2021 is not what astronomers expected. Instead of getting brighter, Leonard actually dimmed.
“This is not good news,” said astronomer at the University of Maryland, USA, who focuses on the comet, Quanzhi Ye. “If Leonard’s comet doesn’t increase in brightness, there must be something wrong with the comet. However, whether it was a mistake, until this stage we don’t know what is going on,” he added.
However, from studies of a number of previous comets, the dimming of the comet’s light as it approaches the Sun may be triggered by the collapse of the comet’s core. In addition, the dimming can be triggered by the depletion of the ice sheet on the surface of the comet’s body that evaporates due to the sun’s heat. However, the hypothesis of the end of the ice sheet is considered less plausible.
However, it is too early to say that Leonard’s comet has been destroyed or dead. The latest images before Leonard reaches his closest point to Earth or before December 12, 2021, show the comet’s core is still fine. However, the comet’s brightness does continue to decline.
According to Ye, the first sign a comet is about to disintegrate is to lose its ionic tail, which is the flow of charged particles from the comet’s body in a direction opposite to the Sun. These ionic tails may disappear hours after the comet ruptures.
Comets like to do the unexpected. Sometimes they disintegrate before reaching perihelion (its closest approach to the Sun) or after reaching perihelion. In fact, the comet could be destroyed when it is at some distance from the Sun. We won’t know when the comet will disintegrate until we actually see it firsthand,” he said.
Therefore, astronomers will continue to make observations while hoping the weather will support it. Only the results of these observations will be able to determine the survival of Comet Leonard’s fate when faced with the magnitude of the Sun’s gravitational pull, whether it survives until it can return to its original home in the Oort Cloud area or it disintegrates and dies.
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